Table 4.

Disorders of consciousness: causes and presentation^4,7,26,28

Cause of disorder of consciousness	Onset	Consciousness	Pupils	Motor	Etiology
Structural or inflammatory	Rapid	Impaired	Unilaterally nonreactive, may progress to bilaterally nonreactive	Motor dysfunction precedes coma; localized findings	Brainstem compression (direct or indirect), seizures, subarachnoid hemorrhage
Metabolic or systemic disorders	Progressive	Impaired	Preserved	Coma precedes motor dysfunction	Hypoxia, anoxia (eg, drowning, strangulation, arterial dissection, cardiac arrest, systemic hemorrhage) Ischemia (eg, embolic, thrombotic, DIC) Systemic disease (eg, cancer, diabetes) Toxin (eg, alcohol, poison, drug overdose) Meningitis (eg, vasculitis, encephalitis) Fluid and electrolyte imbalance Hypoglycemia Therapeutic coma (eg, barbiturate)
Psychiatric			Firmly closed eyes	Normal tone,	Psychogenic/functional (normal muscle tone, eyes firmly closed, EEG shows awake rhythm) Catatonic (appears unresponsive, but is conscious)
Coma of unknown cause	Rapid or progressive	Impaired	Impaired	Impaired	Potentially life-threatening; diagnosis of exclusion

Abbreviations: DIC, disseminated intravascular coagulation; EEG, electroencephalogram; SAH, subarachnoid hemorrhage.